U.S. patent number 7,837,853 [Application Number 11/918,118] was granted by the patent office on 2010-11-23 for process to blend a mineral and a fischer-tropsch derived product onboard a marine vessel.
This patent grant is currently assigned to Shell Oil Company. Invention is credited to Claire Ansell, Richard Hugh Clark, Richard John Heins.
United States Patent |
7,837,853 |
Ansell , et al. |
November 23, 2010 |
Process to blend a mineral and a Fischer-Tropsch derived product
onboard a marine vessel
Abstract
Process to blend a mineral derived hydrocarbon product and a
Fischer-Tropsch derived hydrocarbon product by providing in a
storage vessel of a marine vessel a quantity of mineral derived
hydrocarbon product and Fischer-Tropsch derived hydrocarbon product
such that initially the mineral derived hydrocarbon product is
located substantially above the Fischer-Tropsch derived hydrocarbon
product, transporting the combined products in the marine vessel
from one location to another location, also referred to as the
destination, and obtaining a blended product at arrival of the
marine vessel at its destination.
Inventors: |
Ansell; Claire (Chester,
GB), Clark; Richard Hugh (Chester, GB),
Heins; Richard John (Chester, GB) |
Assignee: |
Shell Oil Company (Houston,
TX)
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Family
ID: |
34940769 |
Appl.
No.: |
11/918,118 |
Filed: |
April 11, 2006 |
PCT
Filed: |
April 11, 2006 |
PCT No.: |
PCT/EP2006/061513 |
371(c)(1),(2),(4) Date: |
October 09, 2007 |
PCT
Pub. No.: |
WO2006/108839 |
PCT
Pub. Date: |
October 19, 2006 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20090093658 A1 |
Apr 9, 2009 |
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Foreign Application Priority Data
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Apr 11, 2005 [EP] |
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05252255 |
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Current U.S.
Class: |
208/15; 518/728;
518/700; 208/19; 114/74R; 208/950 |
Current CPC
Class: |
C10L
1/04 (20130101); C10G 2300/4062 (20130101); Y10S
208/95 (20130101) |
Current International
Class: |
C10L
1/04 (20060101); C10M 101/02 (20060101) |
Field of
Search: |
;208/15,19,950
;114/74R |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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583836 |
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Feb 1994 |
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EP |
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668342 |
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Aug 1995 |
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EP |
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668342 |
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Aug 1999 |
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EP |
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1101813 |
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May 2001 |
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EP |
|
776959 |
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Oct 2004 |
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EP |
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WO9714768 |
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Apr 1997 |
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WO |
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WO9714769 |
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Apr 1997 |
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WO |
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WO9920720 |
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Apr 1999 |
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WO |
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WO9934917 |
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Jul 1999 |
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WO |
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WO0011116 |
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Mar 2000 |
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WO |
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WO0011117 |
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Mar 2000 |
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WO |
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WO0020534 |
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Apr 2000 |
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WO |
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WO0020535 |
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Apr 2000 |
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WO |
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WO0183406 |
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Nov 2001 |
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WO |
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WO0183641 |
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Nov 2001 |
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WO |
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WO0183647 |
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Nov 2001 |
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WO |
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WO0183648 |
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Nov 2001 |
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WO |
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WO02064710 |
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Aug 2002 |
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WO |
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WO02070627 |
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Sep 2002 |
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WO |
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WO02070629 |
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Sep 2002 |
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WO |
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WO02070630 |
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Sep 2002 |
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WO |
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WO02070631 |
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Sep 2002 |
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WO |
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WO03070857 |
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Aug 2003 |
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WO |
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WO2003087273 |
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Oct 2003 |
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WO |
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WO2004035713 |
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Apr 2004 |
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WO |
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WO2004104142 |
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Dec 2004 |
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WO |
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Primary Examiner: McAvoy; Ellen M
Claims
What is claimed is:
1. A process to blend a mineral derived hydrocarbon product and a
Fischer-Tropsch derived hydrocarbon product comprising providing in
a storage vessel of a marine vessel a quantity of mineral derived
hydrocarbon product and Fischer-Tropsch derived hydrocarbon product
such that at loading at least 50 vol % of the Fischer-Tropsch
derived product is present in the lower half of the storage vessel,
transporting said provided-products in the marine vessel from one
location to another destination location thereby blending said
provided-products producing blended product, and obtaining the
blended product at arrival of the marine vessel at the destination
location.
2. The process of claim 1 wherein more than 50% of the boiling
ranges of the mineral and the Fischer-Tropsch derived products
overlap.
3. The process of claim 1 wherein the mineral hydrocarbon product
is a crude mineral oil, a gas field condensate, a plant condensate
or naphtha, kerosene, gas oil, vacuum distillate, deasphalted oil
or a residual fraction of crude oils.
4. The process of claim 3 wherein the blended product is a blend of
a mineral crude oil and Fischer-Tropsch syncrude, a blend of
Fischer-Tropsch derived naphtha and gas field condensate, a blend
of Fischer-Tropsch derived gas oil and mineral derived gas oil or
the blend of a Fisher-Tropsch derived waxy raffinate and mineral
oil derived vacuum distillates and/or mineral oil derived
deasphalted oil.
5. The process of claim 4 wherein a blend of Fischer-Tropsch
derived gas oil and mineral derived gas oil is prepared.
6. The process of claim 5 further comprising adding additives to
the blend while off-loading the blended product from the marine
vessel at the destination location.
7. The process of claim 1 wherein the transport takes place for at
least 10 days.
8. A marine vessel comprising a storage vessel in which is being
conducted by the process of claim 1.
9. The process of claim 1 comprising a subsequent step of directly
using the blended product as an automotive gas oil or as an
industrial gas oil.
10. The process of claim 1 wherein at loading at least 70 vol % of
the Fischer-Tropsch derived product present in the lower half of
the storage vessel.
11. The process of claim 10 wherein at loading at least 90 vol % of
the Fischer-Tropsch derived product present in the lower half of
the storage vessel.
12. The process of claim 1 wherein the blended product at the
destination location, the difference in density between a sample
taken at 10% of the liquid height below the liquid surface, d1, and
the density of a sample taken at 90% of the liquid height below the
liquid surface, d9, such that the ratio d90-d10/d10 is less than
0.01.
Description
PRIORITY CLAIM
The present application claims priority to European Patent
Application 05252255.4 filed 11 Apr. 2005.
FIELD OF THE INVENTION
The invention relates to a process to blend a mineral derived
hydrocarbon product and a Fischer-Tropsch derived hydrocarbon
product.
BACKGROUND OF THE INVENTION
WO-A-2004104142 discloses the blending of a mineral derived
hydrocarbon product and a Fischer-Tropsch derived hydrocarbon
product and subsequent supplying of the blend to a ship.
A process to blend mineral derived gas oil and a Fischer-Tropsch
derived gas oil is described WO-A-03087273. This publication
describes that a mineral derived may be blended in a refinery
environment to achieve a blended product having a certain cetane
number.
Although WO-A-03087273 provides a process to achieve a blend having
a certain quality property it can still be improved in terms of the
blending operation itself. The present process provides such a
solution.
SUMMARY OF THE INVENTION
Process to blend a mineral derived hydrocarbon product and a
Fischer-Tropsch derived hydrocarbon product by providing in a
storage vessel of a marine vessel a quantity of mineral derived
hydrocarbon product and Fischer-Tropsch derived hydrocarbon product
such that initially the mineral derived hydrocarbon product is
located substantially above the Fischer-Tropsch derived hydrocarbon
product, transporting the combined products in the marine vessel
from one location to another location, also referred to as the
destination, and obtaining a blended product at arrival of the
marine vessel at its destination.
Applicants found that a fully blended product can be obtained by
the process according to the invention. The process makes available
a blended product suited for direct use near the customer or at a
refinery for further upgrading. The process eliminates blending
operations at the destination and eliminates the use of multiple
marine vessels to carry the separate blending products to the
destination.
DETAILED DESCRIPTION OF THE INVENTION
The invention is directed to a process to blend a mineral derived
hydrocarbon product and a Fischer-Tropsch derived hydrocarbon
product. The Fischer-Tropsch derived hydrocarbon product is
suitably obtained by converting a mixture of carbon monoxide and
hydrogen in the presence of a suitable Fischer-Tropsch catalyst
under Fischer-Tropsch operating conditions. The catalysts used for
the catalytic conversion of the mixture comprising hydrogen and
carbon monoxide into the Fischer-Tropsch derived paraffinic
hydrocarbon product are known in the art. Catalysts for use in this
process frequently comprise, as the catalytically active component,
a metal from Group VIII of the Periodic Table of Elements.
Particular catalytically active metals include ruthenium, iron,
cobalt and nickel. Cobalt is a preferred catalytically active
metal.
Examples of suitable Fischer-Tropsch synthesis processes are for
example the so-called commercial Sasol process, the Shell Middle
Distillate Synthesis Process or the AGC-21 ExxonMobil process.
These and other processes are for example described in more detail
in EP-A-776959, EP-A-668342, U.S. Pat. No. 4,943,672, U.S. Pat. No.
5,059,299, WO-A-9934917 and WO-A-9920720 and are incorporated by
reference. The Fischer-Tropsch process may be carried out in a
slurry reactor, a fixed bed reactor, especially a multitubular
fixed bed reactor or in a three phase fluidised bed reactor.
Syngas, i.e. the mixture of carbon monoxide and hydrogen used in
the Fischer-Tropsch process may be prepared from various
hydrocarboneous sources such as for example biomass, coal, mineral
crude oil fractions like residual fractions and methane containing
gases, for example natural gas or coal bed methane gas.
The Fischer-Tropsch derived hydrocarbon product is suitably liquid
at 0.degree. C. If the product is not liquid it is preferably kept
in the storage vessel of the ship at conditions at which the
product is liquid. The Fischer-Tropsch derived product can be the
wax such as is directly prepared in the Fischer-Tropsch synthesis
step. Suitably this Fischer-Tropsch synthesis product is first
subjected to a mild hydroisomerisation to reduce the congealing
point of the product and increase its pumpability and to more
easily have the product in the liquid state in the process of the
present invention. Such a product is also referred to as
Syncrude.
The Fischer-Tropsch derived hydrocarbon product may also be the
lower boiling liquid fractions as isolated from the waxy
Fischer-Tropsch product boiling between 35 and 300.degree. C. These
products comprising substantially, i.e. more than 80 wt % of,
normal paraffins, may be shipped as hydrocarbon solvents, as steam
cracker feedstock or as feedstock for the preparation of
detergents.
Alternatively the waxy product is subjected to a
hydrocracking/hydroisomerisation process wherein lower boiling
fractions are obtained, such as for example paraffin products
boiling in the naphtha, kerosene and gas oil boiling range. The
partly isomerised liquid products so obtained may be shipped to end
customers for use as aviation fuel, diesel fuel, industrial gas
oil, drilling fluids, steam cracker feedstock or solvents. The
partly isomerised wax, also referred to as waxy Raffinate, as
obtained in such process steps may advantageously be further
processed by means of solvent or catalytic dewaxing to obtain
lubricating base oils or may be shipped as such to be used as an
intermediate product to base oil manufacturing locations more near
to the end users. Waxy Raffinate is a distillate fraction. Residual
fractions boiling in the base oil range may also be used. However
it may be more difficult to keep these products in a liquid state
during blending. Examples of such processes are described in more
detail in U.S. Pat. No. 6,309,432, U.S. Pat. No. 6,296,757, U.S.
Pat. No. 5,689,031, EP-A-668342, EP-A-583836, U.S. Pat. No.
6,420,618, WO-A-02070631, WO-A-02070629, WO-A-02070627,
WO-A-02064710 and WO-A-02070630, which references are incorporated
by reference. The referred to hydrocracking/hydroisomerisation and
optimal dewaxing steps are thus performed at the Fischer-Tropsch
manufacturing location and the resulting above described liquid
products are suited as the Fischer-Tropsch hydrocarbon products to
be shipped.
The volume ratio between the mineral derived hydrocarbon product
and the Fischer-Tropsch derived product may range in a wide span,
for example between 1:99 and 99:1 and more preferably between 10:90
and 90:10. The mineral derived hydrocarbon product preferably has a
T90 vol % boiling point as measured by ASTM D86, which is greater
than the T50 vol % boiling point of the Fischer-Tropsch derived
hydrocarbon product. More preferably more than 50 vol % and even
more preferably more than 80 vol % of the boiling ranges of the
mineral and the Fischer-Tropsch derived products overlap.
The mineral hydrocarbon product may be any product which is
extracted from a subterranean environment or derivatives therefrom.
Examples of such products are crude mineral oil, gas field
condensates, plant condensates, naphtha, kerosene, gas oil, vacuum
distillates, deasphalted oils, residual fractions of crude oils and
the like.
Examples of combinations for which the present process will find
utility are the blending of mineral crude oil and syncrude,
blending of Fischer-Tropsch derived naphtha and gas field
condensate, blending of Fischer-Tropsch derived gas oil and mineral
derived gas oil and the blending of Fischer-Tropsch derived waxy
raffinate and mineral oil derived vacuum distillates and/or mineral
oil derived deasphalted oil.
Preferably the Fischer-Tropsch derived hydrocarbon product is the
gas oil fraction, preferably as obtained after hydroisomerisation.
The gas oil product may thus be obtained by fractionation of such a
Fischer-Tropsch synthesis product or obtained from a hydroconverted
(hydrocracking/hydroisomerisation) Fischer-Tropsch synthesis
product. Optionally the gas oil may have been subjected to a
catalytic dewaxing treatment. Mixtures of the aforementioned gas
oil fractions may also be used as the Fischer-Tropsch derived
hydrocarbon product. Examples of Fischer-Tropsch derived gas oils
are described in EP-A-583836, WO-A-9714768, WO-A-9714769,
WO-A-0011116, WO-A-0011117, WO-A-0183406, WO-A-0183648,
WO-A-0183647, WO-A-0183641, WO-A-0020535, WO-A-0020534,
EP-A-1101813, WO-A-03070857 and U.S. Pat. No. 6,204,426.
Suitably the Fischer-Tropsch derived gas oil will consist of at
least 90 wt %, more preferably at least 95 wt % of iso and linear
paraffins. The weight ratio of iso-paraffins to normal paraffins
will suitably be greater than 0.3. This ratio may be up to 12.
Suitably this ratio is between 2 and 6. The actual value for this
ratio will be determined, in part, by the hydroconversion process
used to prepare the Fischer-Tropsch derived gas oil from the
Fischer-Tropsch synthesis product. Some cyclic-paraffins may be
present. By virtue of the Fischer-Tropsch process, the
Fischer-Tropsch derived gas oil has essentially zero content of
sulphur and nitrogen (or amounts which are no longer detectable).
These hereto-atom compounds are poisons for Fischer-Tropsch
catalysts and are removed from the synthesis gas that is the feed
for the Fischer-Tropsch process. Further, the process does not make
aromatics, or as usually operated, virtually no aromatics are
produced. The content of aromatics as determined by ASTM D 4629
will typically be below 1 wt %, preferably below 0.5 wt % and most
preferably below 0.1 wt %.
The Fischer-Tropsch derived gas oil will suitably have a
distillation curve which will for its majority be within the
typical gas oil range: between about 150 and 400.degree. C. The
Fischer-Tropsch gas oil will suitably have a T90 wt % of between
320-400.degree. C., a density of between about 0.76 and 0.79
g/cm.sup.3 at 15.degree. C., a cetane number greater than 70,
suitably between about 74 and 82, and a viscosity between about 1.9
and 4.5 centistokes at 40.degree. C.
The above Fischer-Tropsch derived gas oil is preferably blended
with a mineral derived kerosene or gas oil or mixtures of said
kerosene and gas oil. Preferred mineral derived gas oils or
kerosenes are gas oils or kerosenes as obtained from refining and
optionally (hydro)processing of a crude mineral source or the gas
oil or kerosene fraction as isolated from a gas field condensate.
The mineral derived gas oil may be a single gas oil stream as
obtained in such a refinery process or be a blend of several gas
oil fractions obtained in the refinery process via different
processing routes. Examples of such different gas oil fractions as
produced in a refinery are straight run gas oil, vacuum gas oil,
gas oil as obtained in a thermal cracking process and light and
heavy cycle oil as obtained in a fluid catalytic cracking unit and
gas oil as obtained from a hydrocracker unit or the equivalent
kerosene fraction.
The straight run gas oil or kerosene fraction is the fraction which
has been obtained in the atmospheric distillation of the crude
mineral refinery feedstock. The above fractions suitably have an
Initial Boiling Point (IBP) of between 150 and 280.degree. C. and a
Final Boiling Point (FBP) of between 290 and 380.degree. C. The
vacuum gas oil is the gas oil fraction as obtained in the vacuum
distillation of the residue as obtained in the above referred to
atmospheric distillation of the crude mineral refinery feedstock.
The vacuum gas oil has an IBP of between 240 and 300.degree. C. and
a FBP of between 340 and 380.degree. C. The thermal cracking
process also produces a gas oil fraction. This gas oil fraction has
an IBP of between 180 and 280.degree. C. and a FBP of between 320
and 380.degree. C. The light cycle oil fraction as obtained in a
fluid catalytic cracking process will have an IBP of between 180
and 260.degree. C. and a FBP of between 320 and 380.degree. C. The
heavy cycle oil fraction as obtained in a fluid catalytic cracking
process will have an IBP of between 240 and 280.degree. C. and a
FBP of between 340 and 380.degree. C. These feedstocks may have a
sulphur content of above 0.05 wt %. The maximum sulphur content
will be about 2 wt %. Although the Fischer-Tropsch derived gas oil
comprises almost no sulphur it could still be necessary to lower
the sulphur level of the mineral derived gas oil in order to meet
the current stringent low sulphur specifications. Typically the
reduction of sulphur will be performed by processing these gas oil
fractions in a hydrodesulphurisation (HDS) unit.
Gas oil as obtained in a fuels hydrocracker has suitably an IBP of
between 150 and 280.degree. C. and a FBP of between 320 and
380.degree. C.
The cetane number of the blend of mineral derived gas oil as
described above is preferably greater than 40 and less than 70. If
also other properties like for example Cloud Point, CFPP (cold
filter plugging point), Flash Point, Density, Di+-aromatics
content, Poly Aromatics and/or distillation temperature for 95%
recovery comply with the local regulations the blend may be
advantageously used as a diesel fuel component.
Preferably the final blended gas oil product comprising the
Fischer-Tropsch and the mineral derived gas oil will have a sulphur
content of at most 2000 ppmw (parts per million by weight) sulphur,
preferably no more than 500 ppmw, most preferably no more than 50
or even 10 ppmw. The density of such a blend is typically less than
0.86 g/cm.sup.3 at 15.degree. C., and preferably less than 0.845
g/cm.sup.3 at 15.degree. C. The lower density of such a blend as
compared to conventional gas oil blends results from the relatively
low density of the Fischer-Tropsch derived gas oils. The above fuel
composition is suited as fuel in an indirect injection diesel
engine or a direct injection diesel engine, for example of the
rotary pump, in-line pump, unit pump, electronic unit injector or
common rail type.
The final gas oil blend may be an additised (additive-containing)
oil or an unadditised (additive-free) oil. If the fuel oil is an
additised oil, it will contain minor amounts of one or more
additives, e.g. one or more additives selected from detergent
additives, for example those obtained from Infineum (e.g., F7661
and F7685) and Octel (e.g., OMA 4130D); lubricity enhancers, for
example EC 832 and PARADYNE 655 (ex Infineum), HITEC E580 (ex Ethyl
Corporation), VEKTRON 6010 (ex Infineum) (PARADYNE, HITEC and
VEKTRON are trademarks) and amide based additives such as those
available from the Lubrizol Chemical Company, for instance LZ 539
C; dehazers, e.g., alkoxylated phenol formaldehyde polymers such as
those commercially available as NALCO EC5462A (formerly 7D07) (ex
Nalco), and TOLAD 2683 (ex Petrolite) (NALCO and TOLAD are
trademarks); anti-foaming agents (e.g., the polyether-modified
polysiloxanes commercially available as TEGOPREN 5851 and Q 25907
(ex Dow Corning), SAG TP-325 (ex OSi), or RHODORSIL (ex Rhone
Poulenc)) (TEGOPREN, SAG and RHODORSIL are trademarks); ignition
improvers (cetane improvers) (e.g., 2-ethylhexyl nitrate (EHN),
cyclohexyl nitrate, di-tert-butyl peroxide and those disclosed in
U.S. Pat. No. 4,208,190 at column 2, line 27 to column 3, line 21);
anti-rust agents (e.g., that sold commercially by Rhein Chemie,
Mannheim, Germany as "RC 4801", a propane-1,2-diol semi-ester of
tetrapropenyl succinic acid, or polyhydric alcohol esters of a
succinic acid derivative, the succinic acid derivative having on at
least one of its alpha-carbon atoms an unsubstituted or substituted
aliphatic hydrocarbon group containing from 20 to 500 carbon atoms,
e.g., the pentaerythritol diester of polyisobutylene-substituted
succinic acid); corrosion inhibitors; reodorants; anti-wear
additives; anti-oxidants (e.g., phenolics such as
2,6-di-tert-butyl-phenol, or phenylenediamines such as
N,N'-di-sac-butyl-p-phenylenediamine); and metal deactivators.
The additive concentration of each such additional component in the
additivated fuel composition is preferably up to 1% w/w, more
preferably in the range from 5 to 1000 ppmw, advantageously from 75
to 300 ppmw, such as from 95 to 150 ppmw.
In addition to the above gas oil components also a relatively small
portion of an oxygenate type fuel component may be present in the
final blend. to obtain diesel fuel as for example described in
WO-A-2004035713. The oxygenate fuel may be present in a content of
between 2 and 20 wt %; more preferably between 2 and 10 wt % as
measured in the final fuel composition. The oxygenate is an oxygen
containing compound, preferably containing only carbon, hydrogen
and oxygen. It may suitably be a compound containing one or more
hydroxyl groups --OH, and/or one or more carbonyl groups C.dbd.O,
and/or one or more ether groups --O--, and/or one or more ester
groups --C(O)O--. It preferably contains from 1 to 18 carbon atoms
and in certain cases from 1 to 10 carbon atoms. Ideally it is
biodegradable. It is suitably derived from organic material, as in
the case of currently available "biofuels" such as vegetable oils
and their derivatives.
Preferred oxygenates for use are esters, for example alkyl,
preferably C1 to C8 or C1 to C5, such as methyl or ethyl, esters of
carboxylic acids of vegetable oils. The carboxylic acid in this
case may be an optionally substituted, straight or branched chain,
mono-, di- or multi-functional C1 to C6 carboxylic acid, typical
substituents including hydroxy, carbonyl, ether and ester groups.
Suitable examples of oxygenates (iii) include succinates and
levulinates.
Ethers are also usable as the oxygenate (iii), for example dialkyl
(typically C1 to C6) ethers such as dibutyl ether and dimethyl
ether.
Alternatively the oxygenate may be an alcohol, which may be
primary, secondary or tertiary. It may in particular be an
optionally substituted (though preferably unsubstituted) straight
or branched chain C1 to C6 alcohol, suitable examples being
methanol, ethanol, n-propanol and iso-propanol. Typical
substituents include carbonyl, ether and ester groups. Methanol and
in particular ethanol may for instance be used.
The oxygenate (iii) will typically be a liquid at ambient
temperature, with a boiling point preferably from 100 to
360.degree. C., more preferably from 250 to 290.degree. C. Its
density is suitably from 0.75 to 1.2 g/cm.sup.3, more preferably
from 0.75 to 0.9 g/cm.sup.3 at 15.degree. C. (ASTM D4502/IP 365),
and its flash point greater than 55.degree. C. Adding the additives
and/or the oxygenates may be performed at the destination or
on-board the marine vessel as part of the process of the present
invention. Even more preferred is to add, or at least part of, the
additives and/or the oxygenates when off-loading the blended
product from the marine vessel at the destination. Addition is
preferably performed by means of so-called in-line blending. This
is advantageous because the blend as thus obtained can be directly
used as a finished fuel for use as Automotive Gas Oil (AGO) or as
an Industrial Gas Oil (IGO). Thus a separate blending operation in
a blending park at the destination is avoided and a more efficient
process is obtained.
The mineral derived hydrocarbon product can be loaded at the same
location or at a different location from where the Fischer-Tropsch
derived product is loaded to the storage vessel of the marine
vessel. With substantially above is meant that at loading is meant
that at least 50, preferably at least 70 and even more preferably
at least 90 vol %, of the Fischer-Tropsch derived product is
present in the lower half of the storage vessel. When loading the
marine vessel using a bottom filling device the mineral hydrocarbon
product is preferably supplied first and the Fischer-Tropsch
derived product second. With a blended product at the destination
is meant a mixture wherein the difference in density between a
sample taken at 10% of the liquid height below the liquid surface,
referred to as d10, and the density of a sample taken at 90% of the
liquid height below the liquid surface, referred to as d90, is
small, preferably such that the ratio (d90-d10)/d10 is less than
0.01, more preferably less than 0.001. Preferably the duration of
the blending operation during transport to the destination is at
least 10 days, more preferably at least 20 days. Preferably the
marine vessel travels through the more rough water areas in order
to further enhance blending. For this purpose the process is
conducted for more than 90% of its duration at a distance of at
least 10 nautic miles from the coast.
The invention is also directed to the blended product and to the
above marine vessel comprising the blended product as it arrives at
its destination. The invention is also directed to the direct use
of the blended product as a fuel, more preferably as an automotive
gas oil or as an industrial gas oil.
The invention will be illustrated by means of the following
non-limiting examples.
EXAMPLE
A typical mineral derived gas oil (further referred to as AGO) and
a typical Fischer-Tropsch gas oil (further referred to as GTL)
having the properties as listed in Table 1 were used in the
following experiment.
TABLE-US-00001 TABLE 1 Fuel Reference Units AGO GTL Cetane Index
(ASTM D613) 51.5 >74.8 Sulphur mg/kg 7 <5 Vk @ 40.degree. C.
cSt 2.559 3.606 Distillation IBP .degree. C. 167.8 211 50% .degree.
C. 263.5 298 90% .degree. C. 325.3 339 95% .degree. C. 341.6 349
FBP .degree. C. 351.2 354 HPLC Aromatics Total wt % 26.9 0
Two methods of fuel addition were adopted for this assessment,
although the essence of both experiments remained the same. These
method were the Funnel Technique and the Beaker Technique.
The objective of each technique was to minimise turbulence (and
hence mixing) during addition of the second fuel so that the
majority of any mixing of the two fuels was due to the length of
the contact time. Both techniques involved the preparation of
2.times.2 liter glass beakers, one containing 800 ml of AGO, the
other containing 800 ml of GTL. To the AGO, 800 ml of GTL was added
slowly, using a 1 liter glass cylinder, taking approximately 2
minutes to complete (Blend A.) This technique was repeated for the
addition of the AGO (800 ml) to GTL (Blend B). To evaluate blend
homogeneity, densities of the fuel blends were measured after a
period of time at 400 ml and 1200 ml from the bottom of the beaker
to assess the density at bottom and top of each blend. The funnel
technique for fuel addition involved the pouring of the added fuel
over the outer surface of an upside down glass funnel that had its
base (funnel mouth) in contact with the inner walls of the glass
beaker. This was designed to produce fuel addition over a large
surface area, minimise turbulence and hence minimise the mixing of
the two fuel layers during addition of the second fuel.
The beaker technique for fuel addition involved the direct pouring
of the added fuel down the inner wall of the beaker. This produced
fuel addition over a smaller surface area than that of the funnel
technique, more turbulence and hence more mixing of the two fuel
layers during addition of the second fuel.
Density follows, volume/volume, linear blending rules and a
homogeneous 50:50 blend of the AGO and GTL samples studied will
have a theoretical density of 813.3 kg/m.sup.3. Thus density
measurements of the blends can be used to calculate the amount of
each component present.
Table 2 depicts the density results and calculated percentage for
each component sampled at a depth represented by a volume of 400 ml
(bottom), and 1200 ml (top) on the graduated beaker. It should be
noted that the density result of 841.8 kg/m.sup.3 obtained for
Blend A `Bottom`--funnel method, is greater than 841.4
kg/m.sup.3--the density of neat AGO. However, this result does fall
within the reproducibility of the IP365 method, and the result
indicates that the `Bottom` sample is 100% AGO. The time that the
blends were sub sampled for density analysis were not considered to
have to be identical, as the appearance of each blend did not seem
to change over the 24-hour period observed.
TABLE-US-00002 TABLE 2 Time at which Density Fischer- the blend was
of Tropsch Mineral checked layer derived gas oil Method type Blend
ref. Blend configuration (minutes) (kg/m.sup.3) % vol. % vol Funnel
method A GTL on top 135 788.4 94 6 AGO in bottom 841.8 0 100 Beaker
method GTL on top 10 797.7 78 22 AGO in bottom 824.3 30 70 Funnel
method B AGO on top 145 810.9 55 45 GTL in bottom 815.8 46 54
Beaker method AGO on top 7 810.0 56 44 GTL in bottom 816.5 44
56
When considering respective sets of blends A and B for each method,
it is obvious by the percentage of each component present, at both
top and bottom, of each blend that to provide optimum blending
without agitation then the AGO should be added on top of the GTL
and not vice versa.
* * * * *